[Nishanth]

I'm writing a research paper on ways to reduce aerodynamic drag on automobiles and I have a doubt.
I have managed to reduce the drag coefficient of a bus from 0.6 to 0.48. I want to know how to calculate the fuel consumption for both the cases assuming all the other factors remains the same. Is there a direct relationship between the coefficient of drag and fuel consumption?

In simple words, let the drag co-efficient of a certain vehicle be 0.6 and assume I managed to reduce it to 0.5. What will be the fuel consumption for both of my cases assuming the velocity of the vehicle, density of air, rolling resistance, engine efficiency, drivetrain efficiency all remain constant.

Can you please provide me with equation(s) to calculate the fuel consumption with proof so that I can cite the same on my research paper!

Thank you.

[vinerm]

That is doable provided you know the relation between fuel consumption and axle torque. Assuming that everything else is constant does not help since the relation is certainly non-linear due to thermodynamics (and, of course, fluid flow and turbulence) in the engine and friction in the mechanical components. That means, if relation is second or higher order polynomial or of exponential or logarithmic profile, keeping everything else constant does not lead to anything. The maximum you can say is reduction in torque required at the axle for a certain speed. Drag (or its coefficient) is a non-linear function of velocity. So, you can certainly plot a graph of reduction in torque required vs vehicle speed. Beyond that, you need a proper function.